My old LN 8000 is in need of lower ground speed under heavy load (Off road) and just better gearing for this terrain. It has a 8.3 Cummins and a six speed trans. Low gear at working RPM's is about 7Mph. That is way to fast for me and the truck. So i could swap out the transmission. But that would be big money. Maybe more than the truck is worth. Or i have laying out here a Spicer 6041 4 Speed Auxiliary Transmission. Trouble is it has yokes for a medium duty drive line. My truck has a heavy duty drive line. Do they make heavy duty drive line yokes for this transmission? If so where would a person find them? I know it is a little rough. It is a work in progress.
Auxiliary Transmission: Won't you need your drive shafts modified, amunderdog... You'll need a shaft from main, to auxiliary, to differential. Who ever reworks your drive lines, could put on what ever yokes you need. Or, am I thinking wrong here... Might be time to go to bed... LOL OCR...
I are Poor So the "Who ever reworks your drive lines" will most likely be me. That is why i am trying to determine if the larger yokes are available. And if so, Maybe from where?
I think the best way to go is with a 2-speed rear end amunderdog.I know you have the spicer auxiliary on hand,but with the trucks short wheelbase you may have trouble finding room for the auxiliary tranny not to mention the cost of the driveline modifications.Look around at salvage yards ,2-speed rears are common.
You need to find out what the aux. will do. Namely is a low, direct, then with two overdrives, or a double low, low, direct and over. If it only has one low and then direct and overdrive, you aren't really gaining much, because you need to really slow down I'm assuming. The second version would help, but like 25c says, you're going to have driveline issues, as well as mounting, and the worst thing, making the linkage. You can't make the drivelines yourself, because they need to be balanced, and I doubt you have that equipment. Plus you may have to move hangar bearings and such, which means moving the mounts on the frame rail, as well as keeping the angles correct. The two speed rear is a great idea, you can change it yourself, the driveline will bolt right up, and all you have is a cable running to the rear. If you can live with a lower down the road speed, try to find a rear end with a lower gearing. You've got plenty of power with the Cummins, I'm guessing you just would like to crawl around jobsites a little slower, and not have to wind it up so much loaded from uphill stoplights. A slower speed rear would really help this, and if you needed new rear tires, get smaller ones. With just a single axle tractor, you don't need a big 13 or 15/18 sp tranny, and like 25c says, there are a lot of the old 2 sp rear ends around, making your 6 sp actually a 12 sp.
The 2-speed rear end is the best way to g r a lower geared ratio like a 4.10 or 4.33.Either way dont worry about balancing the driveline.Anyone can make a driveline.I usually cut the driveshaft to length ,then drive the yoke in,and install it in the truck.I block up the rear end so I can spin it in the truck while welding the yoke to the driveshaft.I use a dial indicater to index the driveshaft.If you dont have a dial indicater,Use cribbing under the driveshaft to measure if it's out of round.My point is ,if the driveshaft is centerd on the yoke,it wont vibrate or cause trouble.
Auxiliary Transmission: Well, I reckon I can relate to that answer, easier than any post I've read on this site... :yup And, if you ever find the need... you can use my "poor boy shop pit" any time you want... LOL Seems like I've been using the word fairly often myself... LOL... Completely understand, OCR
Not a bad truck, what year is it?
1993 or 94 Model. Spicer 6041 = double low, low, direct and over. Ok So you all like a two speed rear axle. I do not. They do not split that much. and i think i remember them giving a higher ratio to help overcome lower gearing. I already have a 4.10 rear. would have to g to a 5 somthing, then would kill road gear. If i had the jack the easiest fix is to swap the trans. I was hoping there was a seasoned wrench on here that could help me with the yoke problem. The rest i have about figured out. Thanks for the input....................
I don't recall anyone here saying they "liked" the two speed rear. I, instead, read the responses as saying you'd have difficulty fitting a hog box in there on such a short wheel base. That's just the way I was reading it. And for my curiosity, what is "the rest I have about figured out."?
2 spd its possible, that you can search around the wrecking yards, and find both of the ends of your main trans and the aux to marry them together, and then you will only have to shorten your driveline, which you are probably going to have to do, regardless of what path you choose. or... you could go to smaller tires, but I doubt that you could downsize enough to gain enough there..
I'm with the 2 speed rear guys on this one. A lower ratio (5: something's,) will give you the low-low you're looking for, and a pull up on the red button will give you the road speed you'd need I'd imagine. I can't picture you wanting to run down Interstate 40 at mach 1 with the 'ol gal either, so it ought to be about right once you find the proper ratio'd rear. If you find a rear somewhere and don't see a tag on the housing to tell what gears it has, simply count the number of teeth on the ring gear, and the ones on the pinion, and divide the little number into the big one (ex: 52 on ring, 12 on pinion, = 4:33). Mounting that aux box into that short little wheelbased truck might end up being the "mother of all projects" by the time you're done. Plus, if it already has medium-duty yokes on it, and you're wanting to install it into something that already has 1710 series style yokes for example...there may be a mismatched torque issue here...:idea (in other words, not heavy enough.) Although you'd most likely eliminate the need for a carrier bearing because the distance between the gear boxes and rear won't exceed 60", it's still a chore. Even a 'po boy's gonna spend some hard earned money making that work amunderdog. I'd rethink your opinion on the 2 speed rear if I was in your shoes. You can find a lot of old dumps, garbage trucks and all kinds of dead iron around farmers fields and salvage yards with the gears you'd need for short money, and for a Saturday's work underneath it, you'll have quite a nice ride when you're done...:drinkup
Spicer 6041 hawg box I dont know if this will help amunderdog.I pulled out our 1962 gmc 5500 this after noon and took a few pics of the 6041 auxiliary tranny.It measures about 2 feet long between the u-joint flanges.It might fit in your truck.You need the gear shift socket & linkage.The auxiliary gear shift socket will mount on the mainbox.Look around at salvage yards for u-joint yokes and use your imagination and skills to adapt the drive line.Here are some pics.I am only about half seasoned looking forward to well seasoned.
So you can figure out all the other stuff, but need a seasoned mechanic to tell you where to get parts? Everytime I write a reply any further than this I get mean, sarcastic and nasty. hint:truck parts store, driveline shop, salvage yard. Good luck, send pics when you get it done. Ps, nice pics 25c, is the old girl a gasser? bet she grunts full of wet corn! It was a grain hauling king when it was built!
I still have an old Chevrolet truck similar to that my grandad bought new. It is just a tractor, and the old grain trailer is down in our graveyard of tractors and vehicles. It has the 409 gasser in it. It ran 4-5 years ago when I put it in the barn. As far as the gearing problem goes, I would also go with the 2 speed rear end. We have a C-70 that has one mean low gear. When the axle is in high, it will run 60 mph comfortably. I really would not want to drive that thing much faster than that.
The odds are that the rearend you have now won't be able to withstand the extra strain that it will see with the lower gearing of the auxilliary transmission if you install it and you might be looking at replacing the rearend anyway down the road.I would go with the twospeed rearend as the solution and maybe sell the original and auxilliary to help finance it.Ron G
Mine is 21" yoke to yoke mount so 24 total sounds about right. My first drive shaft is about 31" to the carrier bearing. I have seen pictures of a home made direct coupling of Aux and main. It looked way over engineered. Thanks for the pictures. They do help me think.
Sorry. I live way out in the woods. And am not a pro large truck wrench. I heard rummors of a truck wrecking yard about 20Mi from here, in a place that is not on the map. Anyway mostly i wanted to know if anyone ever saw this type of Aux trans with the larger yokes (then i would know they do exist). I know the next size up had them 70 somthing size. If you search around the web you will not find much info on this subject. Nor will you find many parts for said item. Thanks for the reply.
It has a Rockwell RS21145 rear. It should do the job. I believe. Lower trans gears are usually easier on the rear, as you do not get all the jerking around and wheel hop. But isn't that the way it goes? You improve one thing and cause another problem. Guess thats why the big time people just go down and order a truck speced to there requirments.
Have you tried Windrock Truck Parts in Oliver Springs?
I get parts from them occasionally. Have not had much luck getting them to turn loose of used parts. Have been thinking about making the trip over to see what they know.
Low Gears You have gotten lots of free advice here, but I would install a Fuller RT or RTO 613 Transmission or an RT 6613 transmission in this truck with a NO 2 bell housing. RTO has 20% overdrive and first gear is like 15 to 1 RT is direct drive with 18 to 1 first gear and direct in 13th gear. 6 stands for 600 ft of tourque 66 is a newer model with finer gears rated at 650 ft # torque you will pay $1,000 to $3,000 for one I would think. these use air to shift the ranges if that is a problem. A two speed rear axle is nice but the RT 613 is nicer and easier swap over all I think.
How about changing tranny? The fords with 3208 had 13sp had 5 low gears Once you split up it was like a 10 spd Worked really well
Low Gears You have gotten lots of free advice here, but I would install a Fuller RT or RTO 613 Transmission or an RT 6613 transmission in this truck with a NO 2 bell housing. RTO has 20% overdrive and first gear is like 15 to 1 RT is direct drive with 18 to 1 first gear and direct in 13th gear. 6 stands for 600 ft of tourque 66 is a newer model with finer gears rated at 650 ft # torque you will pay $1,000 to $3,000 for one I would think. these use air to shift the ranges if that is a problem. A two speed rear axle is nice but the RT 613 is nicer and easier swap over all I think.
Yes the RT 613 does have 5 gears in low low range but two of them overlap. In low low you go 1-2-3 then you shift to intermdiate and got back to position 1 which is 4th gear.. the two extra forward gears in low low can be used.. What Ford used with the 3208 CAT was the Fuller/ Eaton RT613 and RTO613 and RT6613 and RTO6613 The O is if it has overdrive .. then it changes to a double H shift pattern 13th is in 12th spot on the shifter
lower gearing Lower gearing should not hurt your present rear end you just want to go slower not pull stumps out with it right? The present rear end should be strong enough to spin the tires long before you break anything. Like I said before you are getting lots of FREE advice on here!
Hi fwd sounds like you really know your fullers I needed lower gears in my dump trk &went to a rtlo14613b good choice??
Eaton Transmissions Hello I don't know how much torque your engine has. rtlo 14613b is a very heavy transmission for and engine with 1,400 ft # of torque. The guy who started this thread has a very light duty dump truck witch means the rt613 which is rated for 600# or 650# of torque is perfect for him. The transmission that you used it way to heavy for his needs.
8.3 Cummins Diesel My old LN 8000 is in need of lower ground speed under heavy load (Off road) and just better gearing for this terrain. It has a 8.3 Cummins and a six speed trans. Low gear at working RPM's is about 7Mph. That is way to fast for me and the truck. If you look at the first entry on this blog you will see he has a Ford Dump truck the old white chevy grain truck is the possible donar truck for the auxiliary tranny. A Fuller RT or RTO 613 or 6613 is the best way to go unfortunately I never heard back from the person who started this post.
I have the same problem a few weeks ago with my transmission. I don't do a thing to fix it then one day it is fixed.
Yeah right.
A lot of good and well intended information has been put into this thread - too bad nobody answered his question - can he change u joint sizes
Just my dumb opinion I have a 1956 Ford 10 wheeler they came that way (aux with OD) so I can split any gear I want I can go about as fast as an ant then go on the highway in OD. My self I rather fool with driveshafts then with rear axles, I know what you have for U Joints and have seen auxilliarys with those joints they are out there. Then on the other hand if I was 40yrs younger I probably would fight those nasty U bolts jacking blocking for a 2 speed.
Sorry I forgot to add Maybe to my fortune I have a local Spicer /driveshaft shop that can do all the tricks talking about U joint specialist your just going to match the yokes ie using a spicer aux spicer yokes shouldnt be a problem.
We have a 97 gmc 7500 with a 3116 cat@ 250hp. It came from the factory. With a fuller 6306? 6spd and 4:33 gears. Needless to say we were in the same boat as underdog with it. Our solution after talking to local heavy tranny shop was a reman rt6613. It was a great solution and made a real truck out of a pile of garbage. We couldn't be happier with it. How did you make out amunderdog?
Yes you can change u-joint sizes and yoke sizes and drive shaft sizes. It would be very expensive to buy new parts but you could use all junk yard parts to do this. It still looks like the dump truck is almost too short to add an axillary transmission. I am looking to add a 4 speed auxillary transmission behind and Allison 4 speed. Presently it has a Fuller 2 speed behind it. 2.30 low 1 to 1 high. 7.60 rear axle ratio 67" tall tires and a DT 466 210 HP
Hi i, a new forum member, Jazlawson. (peter lawson)